Over the past five years, the principal investigator (PI) has focused his attention on the respiratory function of the upper airway. Ongoing research seeks to elucidate the factors which modulate the respiratory- related activity of upper airway muscles. In addition, current work seeks to determine the role of upper airway muscles in the pathogenesis of the clinical sleep disorder, obstructive sleep apnea. The Pulmonary Division at UTMB Galveston has provided the PI with the unique opportunity to pursue the answers to these questions in three important areas: animal research, and clinical research during both wakefulness and sleep. Over the next five years, the PI seeks to develop his Animal, Sleep and Clinical Control of Breathing Laboratories into an integrated network for the investigation of physiologic and pathophysiologic aspects of upper airway function. Two other related goals over the next five years are 1) to strengthen collaborative ties with other investigators with primary interests in upper airway function and 2) to develop the expertise in basic neurophysiology which will be applied to studying neuromotor control of the upper airway. In addition to ongoing work on the pathogenesis of obstructive sleep apnea, specific research over the next five years will focus on the role of the larynx in the regulation of respiration in humans. New techniques developed in our laboratory allow electromyographic recordings to be routinely obtained from 3 previously inaccessible laryngeal muscles: the thyroarytenoid, arytenoideus and posterior cricoarytenoid. Support of this application will allow the application of these techniques to determine the factors which control the respiratory-related activity of these intrinsic laryngeal muscles. Correlation of the electromyographic recordings with measurements of laryngeal airway resistance and vocal cord position will be used to determine 1) the physiologic and pathophysiologic factors which control the respiratory-related activity of intrinsic laryngeal muscles, and 2) the net effect of changes in intrinsic laryngeal muscle activity on laryngeal function.